ZXCT1010 ZETEX | Alldatasheet

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Technical content

DESCRIPTION

The ZXCT1010 is a high side current sense monitor. Using this device eliminates the need to disrupt the ground plane when sensing a load current. It is an enhanced version of the ZXCT1009 offering reduced typical output offset and improved accuracy at low sense voltage. The wide input voltage range of 20V down to as low as 2.5V make it suitable for a range of applications. A minimum operating current of just 4µA, combined with its SOT23-5 package make suitable for portable battery equipment.

FEATURES

  • Low cost, accurate high-side current sensing.
  • Output voltage scaling.
  • Up to 2.5V sense voltage.
  • 2.5V – 20V supply range.
  • 300nA typical offset current.
  • 4µA quiescent current.
  • 1% typical accuracy.
  • SOT23 -5 package.

APPLICATIONS

  • Battery Chargers
  • Smart Battery Packs
  • DC Motor control
  • Over current monitor
  • Power Management
  • Level translating
  • Programmable current source ENHANCED HIGH-SIDE CURRENT MONITOR APPLICATION CIRCUIT

ORDERING INFORMATION

PART NUMBER PACKAGE PARTMARKING ZXCT1010E5 SOT23-5 1010 V V I in in out To Load Vout Rsense Rout Load GND ZXCT1010

Voltage on any pin -0.6V to 20V (relative to GND) Continuous output current 25mA Continuous sense voltage V in + 0.5V > Vsense†> Vin – 5V Operating Temperature -40 to 85 °C Storage Temperature -55 to 125 °C Package Power Dissipation (T A = 25°C) SOT23-5 500mW

ELECTRICAL CHARACTERISTICS

Test Conditions TA = 25°C, Vin = 5V, Rout = 100Ω. SYMBOL PARAMETER CONDITIONS LIMITS UNIT Min Typ Max Vin VCC Range 2.5 20 V Iout 1 Output current V sense =0 V Vsense = 10mV Vsense = 100mV Vsense = 200mV Vsense =1 V 0.975 1.95 9.7 0.3 100 1.00 2.00 10.0 115 1.025 2.05 10.3 µA µA mA mA mA I q Ground pin current V sense = 0 V 148µ A Vsense 2 Sense Voltage 0 2500 mV Isense Load pin input current 100 nA Acc Accuracy Rsense = 0.1 Ω Vsense = 200mV -2.5 2.5 % Gm Transconductance, Iout /V sense 10000 µA/V BW Bandwidth RF P in = -20dBm 3 Vsense = 10mV dc Vsense = 100mV dc 300 kHz MHz

1 Includes input offset voltage contribution

2Vsense=Vin-Vload 3 -20dBm=63mVp-p into 50Ω

Load Connection to load/battery I out Output current, proportional to V in-Vload GND Ground SOT23-5 Package Suffix – E5 Top View CONNECTION DIAGRAM + - Vin Load Iout 100Ω SCHEMATIC DIAGRAM 3 4 5NC GND Iout Load VIN

The following lines describe how to scale a load current to an output voltage. Vsense = Vin -V load Vout = 0.01 x Vsense x Rout1 E.g. A 1A current is to be represented by a 100mV output voltage: 1)Choose the value of Rsense to give 50mV > Vsense > 500mV at full load. For example Vsense = 100mV at 1.0A. Rsense = 0.1/1.0 => 0.1 ohms. 2)Choose Rout to give Vout = 100mV, when V sense = 100mV. Rearranging 1 for Rout gives: Rout =V out /(Vsense x 0.01) Rout = 0.1 / (0.1 x 0.01) = 100 Ω TYPICAL CIRCUIT APPLICATION POWER DISSIPATION The maximum allowable power dissipation of the device for normal operation (Pmax), is a function of the package junction to ambient thermal resistance (θja), maximum junction temperature (Tjmax), and ambient temperature (Tamb), according to the expression: P max = (Tjmax – Tamb) / θja The device power dissipation, P D is given by the expression: PD=Iout.(Vin-Vout) Watts Where Rload represents any load including DC motors, a charging battery or further circuitry that requires monitoring, R sense can be selected on specific requirements of accuracy, size and power rating. APPLICATIONS INFORMATION V V I in in out Vout Rsense Rout Rload Load GND ZXCT1010

The above figure shows the ZXCT1010 supporting the Benchmarq bq2954 Charge Management IC. Most of the support components for the bq2954 are omitted for clarity. This design also uses the Zetex FZT789A high current Super-/H9252PNP as the switching transistor in the DC-DC step down converter and the FMMT451 as the drive NPN for the FZT789A. The circuit can be configured to charge up to four Li-Ion cells at a charge current of 1.25A. Charge can be terminated on maximum voltage, selectable minimum current, or maximum time out. Switching frequency of the PWM loop is approximately 120kHz. 100Ω 0.2Ω 100Ω FZT789A BC81725 1kΩ BAS16 10µH FMMT451 140µH ZHCS1000 220Ω SNS pin MOD pin Charger Input To Battery + bq2954 ZXCT1010 support components omitted for clarity + - Vin Load Iout APPLICATIONS INFORMATION (Continued) Bi-Directional Current Sensing The ZXCT1010 can be used to measure current bi-directionally, if two devices are connected as shown below. If the voltage V1 is positive with respect to the voltage V2 the lower device will be active, delivering a proportional output current to Rout. Due to the polarity of the voltage across Rsense, the upper device will be inactive and will not contribute to the current delivered to Rout. When V2 is more positive than V1, current will be flowing in the opposite direction, causing the upper device to be active instead. Non-linearity will be apparent at small values of Vsense due to offset current contribution. Devices can use separate output resistors if the current direction is to be monitored independently. Bi-directional Transfer Function Iout Load 5Vin4 R Iout Load5 Vin 4 V V2sense out Rout -400 -200 0 200 400 Output Current (mA) Sense Voltage (mV) Output Current v Sense Voltage

PCB trace shunt resistor for low cost solution. The figure below shows output characteristics of the device when using a PCB resistive trace for a low cost solution in replacement for a conventional shunt resistor. The graph shows the linear rise in voltage across the resistor due to the PTC of the material and demonstrates how this rise in resistance value over temperature compensates for the NTC of the device. The figure opposite shows a PCB layout suggestion. The resistor section is 25mm x 0.25mm giving approximately 150mΩ using 1oz copper. The data for the normalised graph was obtained using a 1A load current and a 100 Ω output resistor. An electronic version of the PCB layout is available at www.zetex.com/isense APPLICATIONS INFORMATION (Continued) Layout shows area of shunt resistor compared to SOT23-5 package. Not actual size Actual Size

Oldham, OL9 8NP United Kingdom Telephone (44) 161 622 4422 Fax: (44) 161 622 4420 Zetex GmbH Streitfeldstraße1 9 D-81673 München Germany Telefon: (49) 89 45 49 49 0 Fax: (49) 89 45 49 49 49 Zetex Inc

700 Veterans Memorial Hwy

Hauppauge, NY11788 USA Telephone: (631) 360 2222 Fax: (631) 360 8222 Zetex (Asia) Ltd 3701-04 Metroplaza, Tower 1 Hing Fong Road Kwai Fong Hong Kong Telephone: (852) 26100 611 Fax: (852) 24250 494 These offices are supported by agents and distributors in major countries world-wide. This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. For the latest product information, log on to www.zetex.com © Zetex plc 2001 ZXCT1010 ISSUE 4 - DECEMBER 2001 PACKAGE DIMENSIONS SOT23-5 DIM Millimetres Inches MIN MAX MIN MAX A 0.90 1.45 0.035 0.057 A1 0.00 0.15 0.00 0.006 A2 0.90 1.3 0.035 0.051 b 0.35 0.50 0.014 0.020 C 0.09 0.20 0.0035 0.008 D 2.80 3.00 0.110 0.118 E 2.60 3.00 0.102 0.118 E1 1.50 1.75 0.059 0.069 e 0.95 REF 0.037 REF e1 1.90 REF 0.075 REF L 0.10 0.60 0.004 0.024 a° 01 0 01 0